Questions tagged [neurophysiology]

The study of the physiology of the nervous system, with emphasis on transcellular communication, and cellular and molecular processes involved in neural communication.

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Questions concerning synaptic input and dendritic processing

In the article How Spike Generation Mechanisms Determine the Neuronal Response to Fluctuating Inputs, I read (p.11629) I have four questions concerning some formulations: What is "the membrane time ...
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NMDA receptor mediated plasticity figure reference

Because most of this research is over a decade old, finding a paper with a figure that clearly shows that (neuronal) synaptic plasticity (such as long-term potentiation/LTP) is NMDA receptor mediated ...
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Effect and functional role of voltage-gated channels on dendrites [closed]

I'd like to understand better the effect and functional role of voltage-gated channels on dendrites. What I believe to have understood: It is important that a more distal post-synaptical potential (...
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3D Object Modelling in the Brain

Could somebody point out the neuroscience literature dedicated to the modelling of 3D objects in the human mind? I'm interested in the brain regions, and particularly the details of the circuitry, ...
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160 views

Number and function of voltage-independent ion channels

Googling for "voltage-independent" ion channels neurons doesn't give a good overview over the topic (and yields only approx. 50,000 hits, compared to 500,000 hits when searching for "voltage-dependent"...
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How optimal are the distances of voltage-gated ion channels on axons?

In both myelinated and not-myelinated axon segments ("axons" for short) there are theoretically maximal distances of voltage-gated ion channels beyond which propagation of the action potential would ...
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Visual maps of the neuronal membrane

There are lots of visual maps of the brain as a whole, especially the cortex, that show the distribution of "features" over a two-dimensional map, e.g. the Brodman areas (their morphology and their ...
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140 views

What would EEG recordings reveal if their resolution was better?

1. Temporal resolution Of course, we would see higher frequencies. But would these be informative? Aren't the frequencies measured today near the border to noise? 2. Spatial resolution I guess LFP ...
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104 views

To what extent do gonads affect differences in gendered behaviour?

I'm not sure whether this question makes sense, but someone said that they result in gender differentiation on an organisational level in the brain. I'm wondering how important these changes are, in ...
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Distribution of sodium–potassium pumps

How are sodium–potassium pumps distributed over the membrane of a neuron? Where are the most, where are the fewest? Or does this dependent on the type of neuron? Are there known and understandable ...
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Why is extracellular measurement of action potentials so different from intracellular?

I had read in a paper that present a low noise amplifier the following: "...This level of input signal is larger than both typical action potentials (<500μV) and local field potentials (<5 mV). ...
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67 views

Hopfield-like neuron assemblies

There seems to be general agreement that theoretical Hopfield networks (consisting of artifical neurons, namely McCulloch-Pitts neurons) are biologically rather implausible, among other reasons ...
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Does the amplitude of action potentials vary among species?

I would like to ask if the amplitude of action potential in animals(for example zebra finch or other bird) differs from the amplitude of action potential in humans which is approximately 70mV.
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Neural signals amplitude

Can anyone explain me if there is a difference in amplitude of signals between extracellular recording and intracellular recording. I know that the amplitude of neural signals when an action potential ...
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Correlation between morphology of neurons and neurotransmitters

Are there known significant (positive or negative) statistical correlations between the morphology type of neurons and the neurotransmitters that they use (presynaptic, i.e. transmitters that are ...
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414 views

Synaptic connectivity in the newborn's brain

In my understanding, learning is related to the strengthening and weakening of synaptic connections. Very roughly said: Synaptic connections that are used often are strengthened, those that are used ...
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135 views

What biotechnology can be used to treat lazy eye, and possibly cure lazy eye? [closed]

I tried very hard researching and finding the root cause of amblyopia. It is mainly because of imbalance in eye muscle. But, there are a lot more complicated causes of this disease. Thus, I need some ...
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Longest pathway from sensory to motor neurons

How long is the longest pathway a neural signal can take starting from a sensory neuron and ending at a motor neuron (without loops)? [This is a purely theoretical question concerning only the ...
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What would happen if some neurons are unmyelinated?

I know that cold receptors have myelinated axons and heat receptors don't. From a physiological perspective, what could be the consequences if cold receptors were unmyelinated? Would that pose some ...
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How do our eyes detect light at different frequencies?

Here is my confusion: we can see colored light of different wavelengths: form red to violet. To my understanding, these stimuli cause a confirmational change in the photoreceptors in our eyes and ...
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The human brain in numbers II: synaptic connections [closed]

The overall number of synapses in the human brain is roughly 1,000 trillion, i.e. 10,000 synapses per neuron. My question here is three-fold: I assume that each structural type of neuron (basket, ...
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147 views

If action potential is “all or nothing” then how are finely tuned signals sent from one neuron to another?

If the action potential is an "all or nothing" phenomenon, then how is one type of neurotransmitter secreted rather than another? Let's say, for example, if a neuron received an excitatory post ...
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What is the energy cost of an action potential?

As I understand it, ions flow down their electrochemical potentials through ion channels during a neuron's action potential. Otherwise, ion pumps work to restore and maintain the resting membrane ...
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What are negative and positive after potentials?

After depolarization: is the slow repolarization phase which follows a rapid fall in spike potential and extends up to attainment of the RMP level. It is called phase of negative after potential and ...
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545 views

Where are interneurons in Autonomic Nervous System?

According to the following, it implies that preganglionic neurons are interneurons. Interneuron called preganglionic neuron whose cell body is situated in the "intermediolateral" column of spinal ...
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762 views

Purpose of K+ channels in action potential

I understand that they serve to repolarize the neuron after the Na+ influx. What I don't understand is why this is important. Meaning, let's say all the K+ channels disappeared. So now the ...
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112 views

Role of the pupil response in night vision

What are the things that affect the reaction time of pupil light reflex? What I mean to say is, if you are in a bright room, and the light suddenly turns off. The time you spend to see things in the ...
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524 views

What is synaptic bias?

In non linear model of a neuron there was a mention about bias (Bₖ) which was the summation of the synaptic weights. I want to understand what synaptic bias is and their application/use in neuronal ...
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2k views

Renorenal Reflex

According to this: The kidney contains afferent sensory nerve fibers that are located primarily in the renal pelvic wall where they sense stretch. I think the stretch is due to urine. If I am ...
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What is a CAG::ChR2 rat?

I am reading the paper: Pyramidal Cell-Interneuron Interactions Underlie Hippocampal Ripple Oscillations. The authors use CAG::ChR2 rats (for example in Figure 2) and I don't know what it means. I ...
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535 views

Does a generator potential pass along a nerve the same way an action potential does?

I have read that a generator potential is a localized depolarization of a membrane. Does that mean that it does not pass along a neuron the same way an action potential does ? If not, then how do ...
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Do self-exciting neurons exist?

I have two questions concerning self-exciting neurons in the brain. Have directly self-exciting neurons been oberved, i.e. neurons with an axon terminal building a synapse with one of its own ...
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438 views

How are hereditary neural circuits created in the brain during early development?

Whilst our experiences shape the specifics of our brains throughout life, we know that there are a lot of shared properties between us. We all share the same basic layout as, for example, the V1 ...
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What is the actual speed of nerve impulses in humans?

For an undergrad assignment I read a biology paper that mentioned the speed of nerve imuplses to be 440 km/h in myelinated fibers. However, our biology teacher told us that this reported conduction ...
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263 views

Why bipolar neurons in retina transfer information via graded potentials?

Why should bipolar cells prefer graded potentials to action potentials? My attempt: I know that graded potentials are better in processing information since stimulus is directly proportional to ...
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535 views

Why summation takes place at Initial segment?

I know that many EPSPs summate at initial segment to produce action potential. But I don't understand why if EPSP can travel from dendrite to initial segment, then why it doesn't travel further? ...
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Is the bipolar neuron of the retina considered a sensory neuron?

Any neuron that participates in sending impulses from receptors to CNS are referred as sensory neurons. But I often see bipolar neurons of eye(which according to the above definition should be sensory ...
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Is aneuploidy/aneusomy only a problem for cell division?

One of my textbooks states that: "recent studies suggest that aneuploidy can be seen in upwards of 10% of human brain cells without any noticeable effects" I do know that trisomy 21 causes ...
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Why does olfactory sensation need lateral inhibition?

Why does olfactory sensation need lateral inhibition? If it's not helping in spatial discrimination then why is it needed? Don't we just smell the odour which is more concentrated? My attempt: It is ...
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2answers
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Stimulating an axon causes impulses to travel both ways?

A diagram is presented as such above. The question given states What would be the effect of stimulation to cause a nerve impulse with a microelectrode at the middle of the axon? I thought the nerve ...
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Limit of muscle atrophy [closed]

I read that lack of action leads to muscle atrophy , I experienced same when I had a cast for hand fracture. So how far this atrophy go, who decides minimum size of muscle due to lack of activity, for ...
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Why does the “all-or-none” principle hold true for only single nerve cell, and not a bunch of nerve cells?

I've read this from wikipedia: ... This relationship holds only for the unit of tissue; for nervous tissue the unit is the nerve cell, for skeletal muscle the unit is the individual muscle fiber ...
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Behaviour of neuron when membrane potential is maintained at threshold potential or more

Via an external electrode the membrane potential of a neuron or group of neurons can be increased from resting potential of -70 mV to -50 mV or more. This will cause them to fire an action potential. ...
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How do I interpret this depiction of dopamine neuron signaling?

I am studying the work of Wolfram Schultz on reward signals. He depicts dopamine reward signals as shown below, which I do not know how to interpret. Each dot represents an action potential in a ...
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Does the Spinoreticular Tract end in Brainstem?

According to this book on Springer spinoreticular tract is : As the name implies, the tract originates in the spinal cord and terminates in the reticular formation (RF) in the brainstem. While most ...
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Understanding the picture of a synapse

I need help to see exactly what is going on here. According to the textbook here is shown a synapse, but I cannot quite see the things the textbook says are there. From what I understand: (1) At1 and ...
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Why do nerve fibres rotate?

Background: Lemniscus (Latin lēmniscus, ribbon) is a strap of second order nerve fibres which twist as they ascend to the brainstem. Why do these these nerve fibres rotate? What could be the ...
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Chief Sensory Cells

What makes the second order neurons of posterior grey horn of spinal cord to be called as "chief" sensory cells? Why don't we call 1st order, or third order neurons or other second order neurones in ...
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What voltage damages a neuron or a group of neurons?

Neurons are stimulated for research and therapy purposes. How much voltage (current, duration, etc) can a neuron or a group of neurons, in humans, take without being damaged?
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What is two photon calcium imaging?

I have encountered the term "two photon calcium imaging" in a few papers. I have tried to look in the internet but can't understand what this technique actually is. I will be very happy for ...